The old "21 Series" FM for combatives was supersceded a while back. the new one is FM 3-25.150. You can find more information about the Army Combatives Program at http://www.infantry.army.mil/combatives/
I am working extensively with the program in my unit and have also studied aikido for about 10 years now. If you have questions concerning the program I'd be happy to answer them or point you to a competent source.
The only thing I can say is that the program is currently being used by the Army. It is proving to be successful in it's goals, which is BTW, NOT to produce lethal budoka. While some of the applications may be useful to those outside of the Army, I would be hesitant to compare it to budo.
In fact, I think it is not possible to compare arts and kinda silly anyway as each has a different perspective, goals, and philosphy behind it. If it works for you...do it.